In a known co-ordinate measuring system, a switching circuit is constructed and arranged to produce a measuring signal in the form of a train of induced pulses in one of the members when a time variable current is applied to the other of the members. In order to produce the measuring signal, the switching circuit sequentially connects, or activates, each of the grid conductors to a common circuit for only a predetermined period of time during a sampling cycle of all the conductors. When the common circuit is connected to a constant current source, operation of the switching circuit sequentially applies unidirectional current pulses to the conductors of the grid member causing a measuring signal in the form of a train of pulses to be induced in the coil member. On the other hand, when a time variable current (e.g., an alternating current) is applied to the coil, a voltage is induced in each conductor; and operation of the switching circuit causes a measuring signal, in the form of a train of pulses, to appear in the common circuit or bus.
The position of the coil member relative to the grid member can be determined by processing the measuring signal in an evaluator circuit. Specifically, the evaluator circuit sequentially differentiates the measuring signal to yield a voltage whose second zero-axis crossing specifies the coordinates of the coil relative to the table.
An object of the present invention is to provide a new and improved measuring table for a co-ordinate measuring system which simplifies the evaluator circuit.